Biochemistry - Macromolecules

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Biochemistry - Macromolecules

• Carbohydrates, Lipids, Proteins and Nucleic Acids

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Carbohydrates

• Bodys most important source of energy
• Plants are our source of carbohydrates
• Three basics groups of carbohydrates mono
  saccharides, disaccharides and polysaccharides

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Monosaccharides

• Simple sugar molecules made up of chains or rings
  of carbon, hydrogen and oxygen in the ratio of
  121

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Disaccharides

• Sugars made up of two mono saccharides formed by
  dehydration synthesis (or condensation reaction)
  (sucrose is a combination of glucose and fructose

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Complex Carbohydrates Poly saccharides

• Large carbohydrate molecules that are polymers of
  mono saccharides
• Examples starch glycogen, cellulose and chitin
• Structure may be straight, twisted or branching
  chains

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Lipids

• include fats, phospholipids, waxes and steroids
• fats serve as long-term energy storage molecules
• phospholipids forms cell membranes
• steroids include cholesterol and certain sex
  hormones

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FATS

• Fats consist of a wide group of compounds that
  are generally soluble in organic solvents and
  largely insoluble in water.
• Chemically, fats are generally triesters of
  glycerol and fatty acids
• Fats may be either solid or liquid at normal room
  temperature, depending on their structure and
  composition.

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Structure of Fats

• Are made up mainly of two types of molecules
  fatty acids and glycerol
• Fatty acids are long carbon-hydrogen chains with
  a carboxyl (COOH) group at one end

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Triglycerides

• Are long-term energy storage molecules found in
  fat cells of adipose tissue
• Composed of a glycerol molecule and three fatty
  acids

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Trans Fats

• In cis-bonds, the two pieces of the carbon chain
  on either side of the double bond are either both
  up or both down
• In trans-bonds, the two pieces of the molecule
  are on opposite sides of the double bond, that
  is, one up and one down across from each
  other
• fatty acids with trans bonds are carcinogenic, or
  cancer-causing.

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Phospholipids

• Consist of a hydrophilic phosphate molecule and
  two hydrophobic fatty acid tails
• Are and important part of cell membranes

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Steroids

• Consist of four linked carbon rings
• Side chains attached to the rings make individual
  steroids unique
• Include cholesterol, cortisone and the sex
  hormones estrogen and testosterone

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Proteins

• Direct and control the chemical reactions in life
  processes
• Make up part of the cell membrane
• Provide support and shape to cells
• Function as hormones (chemical messengers)
• Function as enzymes to speed up chemical
  reactions
• Make up about ½ the bodys dry weight

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Amino Acids

• Proteins are polymers of amino acids
• AA contain C, H and O like carbohydrates and
  lipids but also contain N
• All AAs have same basic structure
• Each AA varies only in the structure of the R
  group
• There are 20 different AAs, eight of which are
  essential

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Protein Structure

• Proteins can contain more than 1000 AA monomers
  and are known as a polypeptide
• They are formed by dehydration synthesis forming
  peptide bonds between C and N atoms

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• Proper function of proteins is determined by
  shape
• There are four different levels of protein
  structure
• primary,
• secondary,
• tertiary and
• quaternary

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Primary Protein structure

• Is simply the order of AAs in the polypeptide

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Secondary Protein Structures

• Primary structure folds upon itself to form
  a-helix or b-pleated sheet patterns due to
  hydrogen bonding

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Tertiary Protein Structures

• Are formed when the secondary structures fold
  over upon themselves and are held by covalent,
  ionic, hydrogen and non-polar bonds
• The covalent bonds are disulfide bridges between
  Sulphur-containing AAs

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Tertiary Protein Structure

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Quaternary Protein Structure

• Occurs when two or more polypeptide chains
  combine to form the protein

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Protein Denaturation

• Exposing a protein to heat, radiation or change
  in pH will alter its shape
• Physical or chemical factors that disrupt the
  bonds between the amino acids changing the shape
  of the protein is called denaturing
• Sometimes removing the factor allows the protein
  to assume is original shape
• When the change is permanent coagulation has
  occurred

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Nucleic Acids

• Form the hereditary molecule DNA and RNA
• Are polymers formed from monomer molecules called
  nucleotides
• Nucleotides are made up of three subunits a
  nitrogen-containing base, a five-carbon pentose
  sugar molecule and a phosphate group

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Nitrogenous bases

• There are five nitrogenous bases, adenine,
  guanine (the purines), cytosine, thymine and
  uracil (the pyrimidines)
• Thymine is present only in DNA and uracil is
  present only in RNA

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Nucleotide Bases

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DNA Structure

• The DNA molecule is made up with the outer
  backbone of the sugar and phosphate group while
  the bases point inward

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• Double and triple hydrogen bonds link the bases
  of the two chains

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Adenosine Triphosphate (ATP)

• Is an important nucleotide found in the cell
• Is a monomer Consisting of three phosphate groups
  attached to the ribose
• ATP is the energy providing molecule of the cell
  and when the third phosphate group is split off
  by hydrolysis a net release of energy results

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